Kate Middleton is allegedly expecting her second child with Prince William.

In an interview with Australia's New Idea magazine, the Duchess of Cambridge's childhood friend Jessica Hay confirmed the news.

According to Hay, who famously predicted Kate's first pregnancy in November 2012 just weeks before the official announcement, the royal couple will be welcoming their second child very soon.

"Kate's inner circle are buzzing with the news that she is pregnant," Hay told the publication. "I've heard it from several different friends of theirs now and they're saying that they think there's going to be an official announcement in weeks."

Adding on, Hay claims the 32-year-old royal is already showing the first signs of pregnancy and has noticeably changed in appearance in recent weeks.

"Kate's face is fuller like it was when she was first expecting George and she's been changing her hair, which could be to disguise the fullness," Hay said. "She has rosy cheeks, she's letting her greys show again, and whenever she's out in public she goes to great lengths to hold something over her tummy…"

During Kate's first pregnancy, she was diagnosed with hyperemesis gravidarum (acute morning sickness), a "potentially serious" ailment causing vomiting and a bodily reaction against intake of food and liquids. On the day she was rushed to the hospital, the Palace announced she was with child.

However, this time the royal couple will keep the pregnancy under wraps for some time.

"With George, they were forced to tell the world very early on that Kate was pregnant because she was rushed to the hospital with that awful hyperemesis gravidarum at around six or seven weeks," Hay revealed.

This news comes just days before Prince George will celebrate his first birthday on 22 July.

Meanwhile, rumours regarding Kate's second pregnancy have been doing the rounds for a while now.

According to Vanity Fair magazine's royal correspondent Katie Nicholl, palace insiders claim Kate and Prince William will reportedly try for a second baby this summer.

In March, OK! Magazine reported that Kate was pregnant with twin girls, and last month, InTouch Weekly claimed that she is already two months along with a baby boy.